I think it's probably unrealistic to expect new powers and stuff like that, as many resources - programming, art, animation, etc - as they require.
And a couple of the suggestions I know aren't possible - the Cryptic and Paragon teams apparently tried for years to get shapeshifting and size alteration working and it was just a no go in the CoX engine, and they said Speed Melee wasn't really viable because they made speed a movement power.
As someone who has actually added hundreds of additional powers to another private MMO server (not COH) its really not that difficult, you dont NEED to make anything new, you can just take all the parts you have available and assemble them in a different way. If you look through the existing sets you can see the same animations but in a different context which makes them look "different" then you can dress it up with glows or impacts, activation timers and SFX and voila, new sets, inserting new effects isnt even hard.
Bespoke animations and sound however, I couldnt tell you how hard it is to do.
What game?